I disagree that it was a mistake. Proofs in the pudding - Oz went from double digits back, to close or leading, mostly on the fact that voters don't want a brain dead carrot as their Senator.
That topic doesn't get out for debate without Oz bringing it up, himself. Lord knows the media wouldn't - those suck asses would clean the drool off the Zombie's chin during an interview. And Oz couldn't have staffers or surrogates bring it up first - the media would have demanded that he denounce those meanie comments from his people, and the temptation would be to hang them out to dry via denouement / firing.
Oz bringing up the fact that Uncle Fester is brain dead puts the topic out, then lets people on his side pick it up and run with it, knowing the candidate himself has staked his claim to the topic, and that he has the back of others who'll bring it up.
Compare and contrast that with Mittens meekly drawing a circle on the chalkboard and putting his nose in it during the second debate with Obama, when he and Fatty Crowley planned out exactly when and how they were going to "go to the videotape. Go to the videotape!".
Oz is in it to win it, unlike cucks like Mittens or McShitStain in 12 and 08, and that fires the base up, which Oz needed to do after a bruising primary in which he only got a 1/3 of the vote.
Now he doesn't have to bring it up anymore, the topic is out there and at the top of the issues, bringing the Zombie down. But none of this happens if Oz didn't broach the subject first.